Plane tractor

Abstract

The invention relates to a plane tractor which grips the nose gear of a plane, including: a chassis; wheel modules connected to the chassis, each wheel module including at least one actuator for inducing a vertical movement of the module in relation to the chassis; a gripping platform for gripping the nose gear of a plane, the platform together with the chassis having freedom of movement substantially in circular translation; and a damping and actuating means connecting the platform and the chassis.

The invention claimed is: 
     
       1. A method for pulling an airplane by an airplane tractor, the method comprising:
 blocking primary brakes of the airplane; 
 gripping a nose gear of the airplane by a tractor; 
 exerting a pulling force on the airplane by the tractor prior to releasing the preliminary brakes of the airplane; 
 releasing the primary brakes of the airplane, thereby causing the resistance force of the airplane to be less than the pulling force of the tractor; and 
 allowing the pulling force to drive the tractor together with the airplane. 
 
     
     
       2. The method according to  claim 1 , wherein gripping a nose gear of the airplane is performed before blocking primary brakes of the airplane. 
     
     
       3. The method according to  claim 1 , wherein the tractor includes a chassis; wheel modules connected to the chassis, each of the wheel modules includes at least one actuator for inducing a vertical movement thereof in relation to the chassis; a gripping system for gripping the nose gear of an airplane, the gripping system including a gripping platform moveable substantially in circular translation in relation to the chassis, the gripping platform going from a retracted position to a gripping position by way of an equilibrium position; and a damping means and an actuating means connecting the gripping platform and the chassis; and wherein gripping a nose gear of the airplane by a tractor includes:
 actuating the damping and actuating means to place the gripping platform in the retracted position; 
 lowering the chassis; 
 moving the tractor so as to place the retracted gripping platform in contact with at least one wheel of the nose gear of the airplane; 
 actuating the damping and actuating means to move the gripping platform from the retracted position toward the gripping position, while adjusting a height of the chassis by controlling the actuators of at least two of the wheel modules so as to slide the gripping platform under the at least one wheel of the nose gear; 
 raising the chassis; and 
 bringing the gripping platform back to the equilibrium position. 
 
     
     
       4. The method according to  claim 1 , wherein releasing primary brakes of the airplane is performed by the airplane's pilot. 
     
     
       5. The method according to  claim 1 , further comprising accelerating the tractor until the tractor reaches a constant cruising speed. 
     
     
       6. The method according to  claim 1 , further comprising regulating the speed of the tractor as a function of the force measured by the damping and actuating means. 
     
     
       7. The method for pulling an airplane according to  claim 6 , wherein the speed of the tractor is controlled such that the measured force exceeds a dynamically determined threshold level.